Hemi Predator Build #2

[Whitetrashrocker]

Correct on the valve carb sizing. Just slightly smaller carb to help the air rush through it. Better Venturi.

But we built a short rod stroker and had to put 2 bored 850s on it. That 550ci really wanted the air! After it blew it went down a little but long rods and had to go back to just one carb and it still was a little much. It didn't flow the same. It's neat how little changes make a big difference.

 

[KartFab]

I had a few people confirm to me that as a rule of thumb that the carb venturi should be 2 mm smaller than the intake valve diameter, so that is right in line with that.

I wonder what effect that far of advance has on lower/engagement rpms. I was under the impression that the further you advance the timing, the higher in the rpm range the power curve shifts (in conjunction with the cam obviously). Id rather keep timing within the range that the cam card specifies.

Also, a lot of the performance parts and modifications Jody references are applicable for racing, where an engine may live in the 5-7k rpm range, and anything under 4k rpms is irrelevant.

For a yard kart or mini bike, 2200-3600 rpms is usually where you spend most of your time, with short bursts of speed to whatever max rpm youve got, so that is something to keep in mind with timing. Esp if you advance timing too much, you may not even be able to idle at low rpms..... or so i thought.

 

[bob58o]

Right, I thought the same on the timing. I'm assuming when he says 34-36 for gas engines Turing less than 7k, he means turning 6k -7k constantly the entire race. I just found it interesting, cause it was contradicting what I had previously believed.

 

[bob58o]

Getting rid of the lip.
Looking better. Hopefully I don't destroy this head trying to save a few dollars by making the pony powers myself.

But this is the fun part for me.

 

[bob58o]

NR shipment on its way. Going to have to find the 1/4" drive ft-lb torque wrench. I'll use plastiguage to install the rod, but not really sure I'm comfortable surfacing the journal by hand if the oil gap is too tight. And what if it's too big? Send the rod back?

 

[bob58o]

looks like I'll be paying for a valve job after all.

Really want this Neway Valve Seat Cutter...

CU103 - Cutter Body 1.125" (28.575mm)
Dual Cutting Angles
31* for 25mm - 30.5mm valves
46* for 25mm - 32.0mm valves

$123
http://www.ebay.com/itm/Neway-Small...03-/192150973031?_trksid=p2349526.m2548.l4275

60* for 22- 32.5mm valves
http://www.ebay.com/itm/Neway-Small...ash=item2cbd1b74f0:g:hpkAAOSwhQhY54SY&vxp=mtr

$12 for the 5.52mm Pilot (100 or 120 series to fit the cutter top size 0.297)
$17 for the 3/8" T Handle

$150ish gets you 30 / 45 two angle valve jobs on hemi and 3rd gen non hemi heads with the 27/25mm valves.

A bit over two hundo gets you all three angles.

 

[tinamcjittles]

looks like I'll be paying for a valve job after all.

Really want this Neway Valve Seat Cutter...

CU103 - Cutter Body 1.125" (28.575mm)
Dual Cutting Angles
31* for 25mm - 30.5mm valves
46* for 25mm - 32.0mm valves

$123
http://www.ebay.com/itm/Neway-Small...03-/192150973031?_trksid=p2349526.m2548.l4275

60* for 22- 32.5mm valves
http://www.ebay.com/itm/Neway-Small...ash=item2cbd1b74f0:g:hpkAAOSwhQhY54SY&vxp=mtr

$12 for the 5.52mm Pilot (100 or 120 series to fit the cutter top size 0.297)
$17 for the 3/8" T Handle

$150ish gets you 30 / 45 two angle valve jobs on hemi and 3rd gen non hemi heads with the 27/25mm valves.

A bit over two hundo gets you all three angles.

Do you have a lathe to make your own tool for it? If you could make your own insert tooling for the drill press that could work pretty well!

 

[bob58o]

Do you have a lathe to make your own tool for it? If you could make your own insert tooling for the drill press that could work pretty well!

Nope no lathe, I got a cheap drill press from HF and that's about my biggest piece of shop equipment. LOL

It is sold with a T Handle or one of these speed handle ez turn wrench things. I liked it cause I could do it by hand.

 

[bob58o]

Sitting at home waiting for the mailman. Waiting for my buzzer to ring. Will it ring? I called to ask if the guy was going to buzz me or just leave a note. He better buzz. Ugghhh. I hate waiting here.

 

[ezcome-ezgo]

Don't GAB on the delivery guy.

 

[bob58o]

So I check my tracking and it says it was delivered 2 hrs ago. I check and there it is. My box with $250 worth of junk in it sitting on the ground. No buzz. I've been here for 2 hours for nothing.

 

[bob58o]

Thank you Russel for shipping me my stuff fast as heck for cheap as can be. I think I ordered Monday it it's here for now for less than $4 shipping.

Faster than the return phone calls but

 

[bob58o]

285-0211

No Cam Card???
Stock vs .285" 250* duration

 

[bob58o]

Intake lobe barely clears the bottom of the cylinder. How much clearance does it need?

Hard to get a good pic. If you know what your looking at, you might be able to see the intake lobe as it is passing the bottom of the cylinder.

 

[tinamcjittles]

Idk, that seems too close.. Could you get a tiny file in there and take some of the cylinder down? Shouldn't do any damage to remove material there right?

 

[Whitetrashrocker]

Is the piston and crank installed? Gotta put the engine together and tear it apart a few times for things like this.

I'm gonna say you would be safe to clearance that out. Even if the skirt came down that far, you would be fine.

 

[bob58o]

Crank yes. Piston no. Actually the cam wasn't all the way in. More clearance when it is all the way in. Lol. But not too much more.

---------- Post added at 07:12 PM ---------- Previous post was at 06:33 PM ----------

So time to start to reassemble.

Connecting rod first.
Watch this video...
https://www.youtube.com/watch?v=owahpOeLYaw

Measuring the rod journal on the crankshaft with the digital HF calipers gives ~1.188"

Reading the ARC instructions afterwards... It says it should be 1.188"

 

[bob58o]

0.002" Oil Clearence measured by plastiguage.
Shooting for 0.0025" to 0.0030", but no less than 0.002" and no greater than 0.004"

 

[bob58o]

Piston on Connecting Rod. Wrist pin and ring clips installed. Arrow on piston points towards push rods. Holes on con rod are on the arrow side.
Used this assembly lube.

 

[bob58o]

0.030" tween the cam lobe and the cylinder is the minimum clearance according to AKG.

"You can use a feeler gauge between the block and cam lobe to make sure you have at least .030" of clearance. It's difficult to see in this picture, but we added a little extra clearance so we can install a bigger cam in the future."

http://www.affordablegokarts.com/Cam Installation.php

---------- Post added at 09:07 PM ---------- Previous post was at 09:04 PM ----------

Installing Piston Rings and Piston.

Watch this video by KartFab.
https://www.youtube.com/watch?v=vpZcbFXUIQ0